Default dart_support_perfetto to false on FreeBSD (series 0004), because
the pinned Perfetto doesn't build there. The port turns it back on in
GN_ARGS, together with the patch-third__party_perfetto_* backport.
FreeBSD-specific, not submitted upstream yet.
--- runtime/runtime_args.gni.orig	2026-09-29 08:00:52 UTC
+++ runtime/runtime_args.gni
@@ -80,7 +80,8 @@ declare_args() {
   # Whether features that depend on Perfetto should be built. We need
   # to define this to allow excluding code that depends on Perfetto
   # from being built on platforms which have a problem linking in the
-  # Perfetto library, e.g. watchOS.
+  # Perfetto library, e.g. watchOS. Perfetto also does not support FreeBSD
+  # (perfetto/base/build_config.h).
   #
   # We also exclude perfetto support when producing builds which set
   # dart_runtime_mode to release e.g. Dart Product builds or Flutter
@@ -93,7 +94,8 @@ declare_args() {
   # is_watchos may be undefined when Dart SDK is built from the Flutter
   # engine tree.
   dart_support_perfetto =
-      !((defined(is_watchos) && is_watchos) || dart_runtime_mode == "release")
+      !((defined(is_watchos) && is_watchos) || current_os == "freebsd" ||
+        dart_runtime_mode == "release")
 
   # The analyze_snapshot tool is only supported on 64 bit AOT builds.
   build_analyze_snapshot =